We propose a new management strategy for engines equipped with automatic transmissions based on the damage to human health caused by emissions. The damage to human health is quantified by the years of life lost in a population due to disability or early death caused by exposure to pollutants. Various engine emissions share a common factor: damage to human health. Our strategy aims to keep engines running along the line of minimum damage instead of focusing on minimal fuel consumption. We applied the minimum damage strategy to the powertrain of a light vehicle to evaluate its effectiveness. In this work, we discuss this strategy’s effects on continuous variable transmission and seven gears automatic transmission and compare the classic minimum fuel consumption strategy to the minimum damage strategy. The latter results in a 50% reduction in damage compared with the minimum consumption strategy at the expense of an 8% increase in fuel consumption.

Hybrid hydromechanical transmissions are particularly suitable for heavy vehicle and have the potential to provide better efficiencies than other hybrid architectures. However, their study must be carried out with care, since there are many possible transmission configurations and there is not one superior to the others for all applications. The particular complexity of these transmissions requires that design be treated as an optimization problem. In this paper, the optimization procedures of the “non-optimal” type are compared with the “optimal” ones, which are more precise than the former, but much heavier in terms of calculation time. The former consist of two sections. The first one is dedicated to the simultaneous optimization of the layout and components of the non-hybrid hydromechanical transmission; the second one is dedicated to the accumulator only, which can be optimized by means of simple physical laws or by means of a “Design of Experiments “procedure. The “optimal” procedures, on the other hand, proceed with the sizing of the entire hybrid transmission through a mathematical programming problem that can be single or multi-objective. It will be demonstrated that the DOE “non-optimal” procedure provides results very close to those derived from the “optimal” procedures, with considerable savings in calculation times.

The parallel hydraulic hybridization, thanks to its simplicity and high specific power, is a suitable solution for the retrofitting of off-highway vehicles subject to work cycles with frequent stop-and-go. This work is focused on the potential of the low-cost parallel hybrid solutions, i.e. characterized by current-technology components, for a specific class of heavy vehicles: city buses. After functional sizing, the hybrid vehicle was modelled and simulated in the Amesim environment. The comparison with the non-hybridized reference vehicle highlighted an interesting consumption reduction, which in any case varies with the type of route. Finally, an optimization of the hybrid vehicle was carried out by means of genetic algorithms, which led to a further, and not negligible, consumption reduction compared to the hybridized version. Optimization, therefore, can be seen as a tool to overcome those minimum benefit thresholds that manufacturers consider as necessary for the industrialization and marketing of new energy recovery systems.

The hydraulic hybridization of the hydromechanical transmission is an interesting solution to reduce fuel consumption in heavy duty machinery, thanks to the high power peaks recovered in the braking phase and the low cost technology involved. However, hybridization must be carefully considered, as there is no optimal configuration for all applications. For this reason, the design of a hydromechanical transmission must be developed on the basis of the specific data of the vehicle and must tend to optimization. Following this concept, the optimal layout of the hybrid Output Coupled configuration for a particular vehicle application, the reach stacker, was studied in this work. The study will be carried out in two steps: first the optimal layout will be sought based on the continuous formulation of the planetary gear. Subsequently, based on the design parameters obtained, the models of the non-hybrid and hybrid transmission will be simulated for a functional and energy comparison.